The activities of the laboratory involve studies of neurotransmitter and hormone receptors. The principle aim is to increase understanding of the factors that regulate either the densities or properties of these receptors. In this regard two principle types of investigation are carried out. In the first of these the effects of various physiological and pharmacological manipulations on neurotransmitter receptors are investigated. In general these manipulations result in changes in the densities of receptors without inducing changes in either the kinetic or equilibrium properties of the receptor. The other series of investigation involves studies of in vitro factors which modulate receptor properties. These factors include effects of temperature, purine nucleotides, and ions. Most of the experiments to be carried out will involve studies of the binding of radiolabelled antagonists to beta-adrenergic receptors on membranes prepared from a variety of mammalian and non-mammalian tissues. However, studies of binding to intact cultured cells and direct studies of the interactions of labelled agonists with beta receptors on membranes and intact cells will also be carried out. A major goal of this research will be to increase our understanding of the coupling between beta-adrenergic receptors and adenylate cyclase. The reciprocal effects of the receptor on the cyclase and of the cyclase and the guanine nucleotide coupling protein back on the receptor will be explored.